Linerless bore seal closure

ABSTRACT

A closure ( 10 ) that is suitable for attachment to a container ( 20 ) having an end portion defining an opening of the container. The closure ( 10 ) comprises a top portion ( 11 ) and a skirt portion ( 12 ) depending from the top portion. The closure ( 10 ) also has a sealing rib ( 14 ) having a first sealing portion ( 15 ) which is contiguous with the top portion ( 11 ). The first portion ( 15 ) has an inner surface made up of at least a first substantially cylindrical surface portion ( 17 ) lying radially inwardly of the first surface portion ( 17 ). The rib ( 14 ) further includes a second sealing portion ( 16 ) that is separated from the top portion ( 11 ) by the first portion ( 15 ) and which, prior to attachment of the closure to the container, extends inwardly to a free edge. The closure ( 10 ) further has a continuous nub member ( 28 ) extending downwardly and outwardly from the underside of the top portion ( 11 ) and positioned radially inwardly of the first sealing portion ( 15 ). On relative attachment of the closure to the container end portion, the nub member ( 28 ) seals with an inner surface of the container end portion and the sealing rib ( 14 ) seals with at least an outer surface of the container end portion.

TECHNICAL FIELD

[0001] The present invention relates to linerless closures forcontainers including, but not limited to, containers for carbonatedbeverages. More particularly, the invention relates to such closuresthat are formed of a synthetic plastics material and, preferably, moldedin one piece for use in sealing reusable containers.

BACKGROUND ART

[0002] U.S. Pat. No. 5,423,444 discloses a plastics closure for acontainer having an externally screw threaded neck, the closureincluding a top portion and an internally threaded skirt. The closurehas an annular sealing rib which projects downwardly from the undersideof the top portion. The rib includes a first substantially cylindricalportion contiguous with the underside of the top portion and lyingadjacent to or abutting with the skirt, and a second, frusto-conical,portion contiguous with the end of the first portion distal to theunderside of the top portion and extending radially inwardly to acircular free edge. During threaded attachment of the closure with theneck, the second, frusto-conical, portion is engaged by a free end ofthe neck and folded back toward or against the first, substantiallycylindrical portion of the rib to form a gas tight seal between at leastthe outer surface of the neck of the container and the closure.

[0003] U.S. Pat. No. 5,609,263 discloses a variant of the above closurein which there is at the free end of the second portion of the rib athick seal ring of substantially circular cross-sectional shape. The riband the seal ring are dimensioned to engage the free end of the neckwhen the closure is threaded onto the neck such that when the neck isfully screwed into the closure its free end crushes the seal ringdirectly against the inside surface of the top portion of the closure.

[0004] International Patent Application No PCT/AU98/00510 (WO 99/03746)discloses still further variants of the closure described in U.S. Pat.No. 5,423,444. In one variant, the sealing rib of the closure has athird portion connected to the second portion at or adjacent itscircular edge and extending generally in a direction away from the topportion. The third portion is substantially no thicker than the secondportion and has a length longer than its thickness. On attachment ofthis closure to a container, the third portion is positioned between theneck of the container and the underside of the top portion of theclosure.

[0005] The present invention is further directed to a sealing ribarrangement for closures. In particular, the sealing rib arrangementfinds use in circumstances where the container neck has suffered damageprior to application thereto of the closure. Such damage can arise insituations where the container is a reusable container and as such hasbeen used at least once before.

[0006] Any discussion of documents, acts, materials, devices, articlesor the like which has been included in the present specification issolely for the purpose of providing a context for the present invention.It is not to be taken as an admission that any or all of these mattersform part of the prior art base or were common general knowledge in thefield relevant to the present invention as it existed before thepriority date of each claim of this application.

DISCLOSURE OF THE INVENTION

[0007] Throughout this specification, including the claims, the word“comprise” and variants such as “comprises” and “comprising” are used ina non-exclusive sense.

[0008] The present invention relates to a closure for a container, acontainer/closure combination, a method of forming the closure, a moldfor use in making the closure, and a method of capping a container withthe closure.

[0009] In the present specification, the closure is defined as beingsuitable for attachment to an end portion of the container. The endportion of the container to be sealed by the present inventionpreferably has a free end, an outside, preferably cylindrical, surfaceand an inside, preferably cylindrical, surface, the inside surfacedefining a bore. The join between the free end and the inside surfaceand the join between the free end and the outside surface are eachpreferably smoothly curved and define respectively what are hereinaftercalled the inner and outer sealing radii of the end portion of thecontainer. It will be appreciated that the end portion of the containercould be formed without either the inner or outer sealing radii or both.

[0010] According to one aspect, the present invention is a closuresuitable for attachment to a container having an end portion defining anopening of the container, the closure comprising:

[0011] a top portion;

[0012] a skirt portion depending from the top portion, said top portionand skirt portion defining a cavity;

[0013] a first sealing portion which is at least adjacent the topportion and having an inner surface; and

[0014] a second sealing portion separated from the top portion by theinner surface of the first portion;

[0015] said second sealing portion, prior to attachment of the closureto the container, extending at least inwardly into said cavity to a freeedge positioned inwardly of the skirt portion, and the inner surfacehaving a first substantially cylindrical surface portion lying radiallyinwardly of the skirt portion and at least a second substantiallycylindrical surface portion lying radially inwardly of the first surfaceportion.

[0016] In one embodiment, the first surface portion is cylindrical. Inanother embodiment, the second surface portion is cylindrical. In astill further embodiment, both the first and second surface portions arecylindrical.

[0017] In another embodiment, the first surface portion is preferablycloser to the top portion of the closure than the second surfaceportion. In one embodiment, the first surface portion can be contiguouswith the underside of the top portion.

[0018] In one embodiment, the transition between the inner diameter ofthe first surface portion and the smaller inner diameter of the secondsurface portion of the inner surface of the closure is relativelyabrupt. In another embodiment, the transition between the inner diameterof the first surface portion and the second surface portion isrelatively gradual. In the latter case, the inner surface can have atransition surface between the first surface and the second surface. Thetransition surface can be substantially frusto-conical and is, morepreferably, frusto-conical.

[0019] In a preferred embodiment, the closure further comprises anannular sealing rib. The annular sealing rib preferably includes thefirst sealing portion defined above. In a further embodiment, the firstsealing portion of the sealing rib can be contiguous with the topportion and project downwardly from an underside of the top portion.

[0020] In a still further embodiment, the sealing rib can also includethe second portion defined above. In this embodiment, the second portionis preferably contiguous with the first portion. More preferably, thesecond portion is contiguous with an end of the first portion distal thetop portion. The second portion can extend for a length inwardly anddownwardly from the distal end of the first portion to a circular freeedge. In one embodiment, the second portion can be at leastsubstantially frusto-conical, and, more preferably, frusto-conical, forat least a portion of its length.

[0021] The second sealing portion preferably is molded at an angle ofbetween about 25° and 75° relative to a notional plane extending at aright angle to the skirt portion of the closure. The angle is morepreferably between about 40° and 50° relative to the notional plane andmost preferably about 44.5° relative to the notional plane.

[0022] In one embodiment, the second portion can firstly extend bothinwardly and downwardly from the distal end of the first portion andthen extend just downwardly for a length to the free edge. In anotherembodiment, the second portion can be non-linear. In this regard, thesecond portion can be partially or continuously curved.

[0023] In a preferred embodiment, the length of the second portion issuch that, during attachment of the closure with the end portion of thecontainer, the end portion of the container contacts the second portionand pushes it upwardly and preferably at least towards the first sealingportion of the closure.

[0024] More preferably, the internal diameter of at least the secondsurface portion of the inner surface of the closure relative to theexternal diameter of the end portion of the container is such that thesecond sealing portion, on attachment of the closure, is folded backagainst the second surface portion of the inner surface. In thisembodiment, a seal is at least formed between the closure and at leastthe outer surface of the end portion of the container at a position awayfrom the free end of the container end portion.

[0025] The radially inward position of the second surface portion of theinner surface serves to increase the force of the pressure of thesealing rib against the outside surface of the end portion of thecontainer at a region distal the free end of the end portion onattachment of the closure to the end portion.

[0026] In a further embodiment, the underside of the top portion of theclosure and positioned radially inwardly of the inner surface of thefirst sealing portion of the closure. The nub is preferably positionedsuch that, during relative attachment of the closure with the endportion of the container, the nub contacts the inner surface of the endportion of the container.

[0027] In a preferred embodiment, the nub comprises a continuous memberhaving an inner surface, an outer surface, and an end distal the topportion. The nub preferably extends downwardly and outwardly from thetop portion. The nub is preferably substantially frusto-conical. Inanother embodiment, the inner and outer surface are non-parallel butremain a substantially constant distance apart for at least a portion ofthe length of the nub extending downwardly from the top portion.

[0028] The outer surface of the nub preferably includes a contactsurface that extends upwardly from the distal end of the nub for aportion of the outer surface. The contact surface contacts the innersurface of the container end portion. The contact surface is defined byan end region of the nub where it tapers in width towards its distalend. The contact surface is preferably curved and seals with the innersurface of the container end portion at a region distal the free end ofthe end portion of the container.

[0029] The nub preferably extends downwardly from the top portion for alength substantially equal to the length of the inner surface of thefirst sealing portion. In a still further embodiment, the thickness ofthe top portion of the closure between the outer surface of the nub andthe inner surface of the first sealing portion can be greater than thethickness of the top portion inwardly of the nub.

[0030] The closure is preferably provided with a screw thread on aninside surface of the skirt portion that is engageable with acorresponding thread on an external surface of the end portion of thecontainer. It is, however, possible for the container and the closure tobe formed with other complementary attachment arrangements. Such anarrangement could, for instance, comprise a snap-on attachmentarrangement having a rib on the inside surface of the closure and acorresponding groove on the outside surface of the end portion of thecontainer.

[0031] The first sealing portion can comprise a thickening of the skirtportion in the region adjacent the top portion and, more preferably, inthe region adjacent it connection to the top portion. By comprising sucha thickening, the root of the second sealing portion, when contiguouswith the first sealing portion, is moved inwardly of the part of theskirt portion having the screw thread or other attachment arrangement.

[0032] In another embodiment, the first sealing portion is formedradially inwardly of the skirt portion with an annular spacetherebetween. In a still further embodiment, the first sealing portioncan be in abutment with the skirt portion over all or a portion of itslength.

[0033] According to a second aspect, the present invention is a closuresuitable for attachment to a container having an end portion defining anopening of the container, the closure comprising:

[0034] a top portion;

[0035] a skirt portion depending from the top portion, said top portionand skirt portion defining a cavity;

[0036] an annular sealing rib having, prior to attachment of the closureto the container, at least a portion extending inwardly into said cavityto a free edge; and

[0037] a continuous nub member extending downwardly and outwardly fromthe underside of the top portion and positioned radially inwardly of thesealing rib,

[0038] wherein on relative attachment of the closure to the containerend portion, the nub member seals with an inner surface of the containerend portion and the annular sealing rib seals with at least an outersurface of the container end portion.

[0039] In this second aspect, the outer surface of the nub preferablyincludes a contact surface that extends upwardly from an end of the nubdistal the top portion for a portion of the outer surface. The contactsurface can contact the inner surface of the container end portion. Thecontact surface is preferably defined by an end region of the nub whereit tapers in width towards its distal end. The contact surface ispreferably curved and seals with the inner surface of the container endportion at a region distal the free end of the end portion.

[0040] In the second aspect, the sealing rib can have a first sealingportion and a second sealing portion as defined above with respect tothe preferred features of the first aspect of the present application.

[0041] In the second aspect, the nub preferably extends downwardly fromthe top portion a length substantially equal to the length of the innersurface of the first sealing portion of the closure. In a still furtherembodiment of the second aspect, the thickness of the top portion of theclosure between the outer surface of the nub and the inner surface ofthe first sealing portion can be greater than the thickness of the topportion inwardly of the nub.

[0042] According to a third aspect, the present invention is a closuresuitable for attachment to a container having an end portion defining anopening of the container, the closure comprising:

[0043] a top portion;

[0044] a skirt portion depending from the top portion, said top portionand skirt portion defining a cavity;

[0045] a sealing rib having:

[0046] a first sealing portion which is at least adjacent the topportion and having an inner surface, said inner surface having a firstsubstantially cylindrical surface portion lying radially inwardly of theskirt portion and at least a second substantially cylindrical surfaceportion lying radially inwardly of the first surface portion; and

[0047] a second sealing portion, separated from the top portion by theinner surface of the first portion and having, prior to attachment ofthe closure to the container, at least a portion extending inwardly intosaid cavity to a free edge; and

[0048] a continuous nub member extending downwardly and outwardly fromthe underside of the top portion and positioned radially inwardly of thefirst sealing portion;

[0049] wherein on relative attachment of the closure to the containerend portion, the nub member seals with an inner surface of the containerend portion and the sealing rib seals with at least an outer surface ofthe container end portion.

[0050] In a preferred embodiment of the third aspect, the length of thesecond sealing portion of the sealing rib is such that, duringattachment of the closure with the end portion of the container, the endportion of the container contacts the second portion and folds it atleast towards the inner surface of the first sealing portion. Morepreferably, the internal diameter of the inner surface of the closurerelative to the external diameter of the end portion of the container issuch that, the second portion, on attachment of the closure, is foldedback against the inner surface. In this embodiment, a seal is at leastformed between the sealing rib and the outside surface of the endportion of the container.

[0051] In the third aspect, the sealing rib can have the features asdefined above with respect to the preferred features of the first aspectof the present application.

[0052] The closures as defined above may be molded from a syntheticplastics material. It is preferred that the closure is formed from asuitable grade of polyethylene or polypropylene. It is also preferred toform the closure in one piece. The closures could, however, be formed intwo or more parts with at least the sealing rib and/or the nub formedseparately from the top portion and the skirt portion.

[0053] It will be apparent to persons skilled in the art that numerousmodifications may be made to the closures described in thisspecification without departing from the scope of the invention asearlier defined. The closure may, for instance, be provided with atamper evident band that provides an indication of removal or attemptedremoval of the closure from a container. The tamper evident band can beattached to the skirt portion by a frangible connection or region, suchas a plurality of frangible bridges.

[0054] As is described in Australian Patent No 668197, the contentswhereof are incorporated herein by reference, the band can also comprisea generally cylindrical body portion and a segmented rib extendinginwardly of the body portion that provides a lip having an inner freeedge to engage under a retaining flange extending outwardly from the endportion of the container. The combined length of the segmented ribs canbe equal to at least 50% of the separated from each other by a gap. Eachof the rib segments can each have an upper surface facing generallytowards the top portion of the closure and an underside facing generallyaway from the top portion, with the inner surface of the band having aplurality of radially inward projections extending from above the freeedge of the band and not extending beyond the inner free edge of thelip.

[0055] As is described in Australian Patent No 683598, the contentswhereof are incorporated herein by reference, the upper surface of eachrib segment extending inwardly of the body portion can be a compoundsurface and comprise a first surface contiguous with the body portion ofthe band, which surface has a slope that slopes inwardly and downwardlyaway from the top portion, and a second surface which extends radiallyinwardly from the inner terminus of the first surface and has a slopeangle substantially normal, and preferably normal, to the skirt portionof the closure.

[0056] As is described in U.S. Pat. No. 5,676,269, the contents whereofare incorporated herein by reference, the tamper evident band can bejoined to the skirt portion of the closure by a plurality of frangiblebridges and at least one non-frangible bridge. The band can further havea substantially L-shaped slot extending through the side wall of theband, the horizontal leg of which terminates directly adjacent to orunder the non-frangible bridge, and a weakened frangible regionextending from the terminating end of the horizontal leg axiallydownwardly to the bottom of the band distal the frangible bridges.

[0057] As is described in U.S. Pat. No. 5,782,369, the contents whereofare incorporated herein by reference, the upper surface of the secondportion of the sealing rib can have, at or adjacent its free end,engagement ridges that engage with the underside of the upper surface ofthe closure on sealing of the closure to an end portion of a container.The engagement ridges can comprise one or more ridges that frictionallyengage with the underside of the top portion of the closure. The ridgeson the upper surface of the second portion of the rib can engage withcomplementary ridges formed on the underside of the top portion of theclosure, on sealing of the closure to a container.

[0058] Where the closure has a screw thread on the inner surface of theskirt portion, the thread can be continuous or formed of a series ofthread segments. If formed from a series of thread segments, the threadsegments can be arranged, starting from a first thread segment distal tothe top, along a helical thread locus, as is described in AustralianPatent No 668197. Each of the thread segments except the first can beformed with two substantially planar end surfaces that are inclined tothe axis of the closure and face away from the top of the closure, thatis they face in the direction that a mold core used to mold the closurewas withdrawn. In this specification, the term “substantially planarsurface” is used to describe a surface that is nearly actually planar orthat is curved provided that it all faces in the defined direction. Thefirst of the thread segments is preferably pointed at its end distal toits one adjacent thread segment to assist in mating the thread on theclosure with a complementary thread on the end portion of a container.

[0059] The substantially planar ends of the thread segments can also beinclined to a notional radial plane of the closure extending from thelongitudinal axis of the closure to the end of the respective threadsegment such that the ends are inclined to the cylindrical skirt by anangle that is less than the angle that the respective notional planemakes with that skirt.

[0060] To assist in the venting of any gas that may be present in thecontainer, the spaces between the thread segments in adjacent turns ofthe thread can be aligned. A groove may also be provided on the insidesurface of the skirt portion of the closure extending longitudinallythereof through the aligned spaces.

[0061] There also can be at the line of meeting of the first and secondportions of the sealing rib, a weakened zone or annular region ofweakness to assist even deformation of the second portion relative tothe first as the closure is attached to a container as is described inAustralian Patent No 637706, the contents whereof are incorporatedherein by reference.

[0062] In a further aspect, the present invention comprises a containerhaving an end portion defining an opening of the container, the endportion being sealed by a closure as defined herein.

[0063] In this further aspect, the container can be a container for acarbonated beverage, a gaseous beverage, or a still beverage. Thecontainer can be formed from polyethylene terephthalate (PET) orco-polymers thereof.

[0064] In a still further aspect, the present invention comprises a moldfor forming a closure as defined herein. The mold can be used to formthe closure using injection, rotary or compression moulding. The moldpreferably has a cavity that defines one or more of the features of theclosure as defined above. It will be appreciated by persons skilled inthe art that other suitable techniques for forming the closure couldalso be utilised.

[0065] In yet a further aspect, the present invention comprises a methodof applying a closure as defined herein to an end portion of acontainer, the method comprising the step of turning the closure ontothe end portion of the container until the closure seals the container.

BRIEF DESCRIPTION OF THE DRAWINGS

[0066] The following description of a preferred embodiment of thepresent invention is provided as an example of the invention and isdescribed with reference to the accompanying drawings, in which:

[0067]FIG. 1 is a simplified diametrical sectional view through a partof a closure according to one aspect of the present invention;

[0068]FIG. 2 is a simplified diametrical sectional view through the partof the closure depicted in FIG. 1 depicting the action of the sealingrib on attachment of the closure to an end portion of a container;

[0069]FIG. 3 is a partial view of an alternative embodiment of a closureaccording to the present invention; and

[0070]FIG. 4 is a cross-sectional view of a closure showing one possiblearrangement of the thread on the skirt of the closure and the tamperevident band.

BEST MODE FOR CARRYING OUT THE INVENTION

[0071] One embodiment of a closure according to the present invention isdepicted generally as 10 in FIGS. 1 and 2.

[0072] The closure 10 shown in FIG. 1 is moulded from a syntheticplastics material in a suitable mold. Such a mold has cavity definingthe features of the depicted closure. The closure 10 comprises acircular top 11 and a depending skirt 12. The radially inner surface ofthe skirt 12 is provided with a screw thread that mates with acorresponding thread on the neck of a bottle 20 to which the closure 10is attached. While the embodiment of the closure 10 depicted in thedrawings is described herein as having a screw thread, other suitablemating arrangements between the closure to the bottle 20 would beimmediately apparent to a person skilled in the art.

[0073] The radially outer surface of the depicted skirt 12 carries aseries of fine vertical ribs 13. The fine ribs 13 in the depictedembodiment terminate at the lower edge of the skirt 12 in a narrowcircumferential rib.

[0074] A sealing rib 14 is provided on the underside of the top 11 ofthe closure 10. The rib 14 is continuous and annular. Seen incross-section, the rib 14 has two portions 15 and 16. The first portion15 is contiguous with the top 11 and, in the depicted embodiment,comprises a thickening of the skirt 12 adjacent the top 11. It will beappreciated that the first portion 15 could be formed radially inward ofthe skirt 12 such that there is an annular space therebetween, as isdepicted in FIGS. 3 and 4. It is also conceivable that the first portioncould be molded such that it was in abutment with the skirt 12 for allor some portion of its length.

[0075] The inner surface of the first portion 15 has a firstsubstantially cylindrical surface portion 17 and a second substantiallycylindrical surface portion 18. As depicted, the second surface portion18 is disposed radially inwardly of the first surface portion 17. Theinner surface has an intermediate, substantially frusto-conical, region19 where the thickness of the first portion 15 gradually increases inthickness. While a relatively gradual transition is depicted between thesurface portions 17 and 18, a relatively abrupt transition could also beprovided (as is depicted in FIG. 4).

[0076] The second portion 16 of the rib 14 is frusto-conical in form andis of substantially constant thickness as it extends radially downwardlyand inwardly from its outer edge which is contiguous with the lower endof the first portion 15. While depicted as being of substantiallyconstant thickness, it will be envisaged that the second portion 16 cantaper slightly in thickness as it extends radially inwardly from itsouter edge. As depicted, the upper surface of the second portion 16 canhave a series of ridges 30. As depicted in FIG. 2, the ridges 30 canengage with the underside of the top 11 of the closure 10 on sealing ofthe closure 10 to the end portion of the container 20.

[0077] A relatively sharp edge can be formed at the line of meetingbetween the first portion 15 and the second portion 16. The sharp edgecan be used to define a line of relative weakness between the twoportions for a purpose that will be described later in thisspecification.

[0078] The underside of top 11 of the closure 10 depicted in FIGS. 1 and2 has a nub 28 extending downwardly and outwardly from the underside ofthe top 11. The nub 28 is positioned radially inwardly of the sealingrib 14. The depicted nub 28 is continuous and has an inner surface 29and an outer surface 31. The nub 28 extends downwardly from the top 11for a length substantially equal to the length of the inner surface ofthe first portion 15 of the sealing rib 14.

[0079] The thickness of the top 11 of the closure 10 between the outersurface 31 of the nub 28 and the inner surface of the first portion 15of the sealing rib 14 is the same as the thickness of the top 11inwardly of the inner surface 29 of the nub 28. In another embodiment,the thickness of the respective regions of the top 11 could varyrelative to one another.

[0080] The bottle 20 to be sealed by the closure 10 has a neck having anend portion 40. In the depicted embodiment, the bottle 20 is areturnable polyethylene terephthalate (PET) bottle. Such bottlestypically have a thicker end portion 40 than non-returnable PET bottlesof similar capacity. The end portion 40 has a free end 41, an outsidecylindrical surface 42 and an inside cylindrical surface 43, with theinside surface 43 defining a bore 43 a. The join between the free end 41and the inside surface 43 and the join between the free end 41 and theoutside surface 42, on the bottle 20 are each smoothly curved anddefine, respectively, inner and outer sealing radii 44,45 of the endportion 40 of the bottle 20. While the present closure 10 can sealbottles 20 having the depicted end portion 40, it will be readilyappreciated that the closure 10 can seal bottles having different endportion configurations, eg. no outer and no inner sealing radii, or onlyone of the outer or inner sealing radii.

[0081] When the closure 10 is applied to and turned onto the end portion40 of a bottle 20, the free end 41 of the end portion 40 engages thesealing rib 14 and starts to push the second portion 16 relativelyupwardly within the closure 10. As the second portion 16 is pushedupwardly it bends relative to the first portion 15 along the line ofweakness. This ensures that the folding of the second portion 16relative to the first portion 15 takes place generally evenly around thewhole circumference of the rib 14. As the closure 10 continues to beturned onto the bottle 20, the second portion 16 is folded back towardsthe inner surface of the first portion 15. At about this time, the nub28 also starts to abut the inside surface 43 of the end portion 40.

[0082] Once the closure 10 is fully turned onto the end portion 40, thesealing rib 14 is positioned between the end portion 40 and theunderside of the top 11 of the closure 10. As depicted, the secondportion 16 has been folded, in this case, back into contact with thesecond cylindrical surface portion 18 of the first portion 15. Thesecond portion 16, while folded back against the surface 18, also bearsagainst the outside surface 42 and onto the outer sealing radius 45 ofthe end portion 40.

[0083] With the closure 10 fully engaged on the bottle 20, the nub 28also exerts an outwardly directed pressure on the inside surface of theend portion 40. Once the closure 10 is fully turned onto the end portion40, a seal is formed between the nub 28 and the inside surface 43 of theend portion 40. A seal is also formed between the rib 14 and the endportion 40. In the depicted embodiment, the seal extends from theoutside surface 42 up around the outer sealing radius 45. Depending onthe capping torque, the seal may also extend across the free end 41 fora distance, such as is depicted in FIG. 2.

[0084] It will be appreciated that the degree of sealing engagement ofthe second portion 16 with the free end 41 of the end portion 40 willdepend on a number of factors, including the relative length of thefirst and second portions, the wall thickness of the end portion 40, andthe capping torque used to turn the closure 10 onto the end portion 40.

[0085]FIG. 3 depicts an alternative embodiment of the closure accordingto the present invention. This embodiment is identified by numeral 50.Closure 50 is similar to the closure depicted in FIGS. 1 and 2 but doeshave a number of key differences. Firstly, it will be noted that closure50 is not depicted as having a nub. While not depicted in FIG. 3, theclosure 50 could be modified to include a nub, such as nub 28 of FIGS. 1and 2. Further, the first sealing portion 15 of the sealing rib 14 isspaced inwardly from the skirt 12.

[0086] Closure 50 is also depicted as having a screw thread 55, and atamper evident band 56 connected to the distal edge of the skirt 12 by anumber of frangible bridges 57.

[0087]FIG. 4 depicts a still further embodiment of the closure depictedin FIG. 3. This closure is depicted generally as 60.

[0088] In this embodiment, the inner surface of the first portion iscomprised of inner surfaces 17 and 18. These surfaces are separated byan abrupt transition 61. Again, the first portion 15 of the sealing rib14 is spaced inwardly from the skirt 12.

[0089] The internal wall of the skirt 12 has a thread made up of aseries of thread segments 51 arranged in spaced apart array along thelocus of the thread. Each thread segment, except the first segment 52,is bounded at each end by a planar surface 53. Each of the planarsurfaces 53 is inclined to the longitudinal axis of the closure 60 sothat it faces away from the top 11. Each planar surface 53 is alsoinclined relative to a notional radial plane extending from the axis ofthe closure 60 to the planar surface 53 in question.

[0090] The first thread segment 52 is formed with a planar surface 53 onits trailing edge but is formed with a pointed leading edge 54 to assistin mating the thread on the closure 60 with a corresponding thread onthe end portion of the neck of a container.

[0091] The thread segments 51 in each turn of the thread are aligned asare the spaces between them. A groove 43 is formed on the inside surfaceof the skirt 12 in each of the aligned spaces between adjacent threadsegments 51. The grooves 43 serve to assist in venting gas from abeverage container as the closure 60 is unscrewed.

[0092] The skirt 12 of closure 60 terminates at its lowest edge in acircumferential rib 62. Below the rib 62, a tamper evident band 63 isjoined to the skirt 12 by a plurality of frangible bridges 64. The innersurface of the band 63 has a rib made up of a series of rib segments 65that extend inwardly and provide a lip having an inner free edge toengage under a retaining flange extending outwardly from the end portionof the container. The combined length of the rib segments 65 is greaterthan 50% of the internal circumference of the band 63 and the ribsegments are separated from each other by a gap 66. Each of the ribsegments 65 have an upper surface facing generally towards the top 11and an underside facing generally away from the top 11. The innersurface of the band 63 also has a plurality of radially inwardprojections 67 extending from above the free edge of the band and notextending beyond the inner free edge of the lip.

[0093] It will be appreciated by persons skilled in the art thatnumerous variations and/or modifications may be made to the invention asshown in the specific embodiments without departing from the spirit orscope of the invention as broadly described. The present embodimentsare, therefore, to be considered in all respects as illustrative and notrestrictive.

1. A closure suitable for attachment to a container having an endportion defining an opening of the container, the closure comprising: atop portion; a skirt portion depending from the top portion, said topportion and skirt portion defining a cavity; a first sealing portionwhich is at least adjacent the top portion and having an inner surface;and a second sealing portion separated from the top portion by the innersurface of the first portion; said second sealing portion, prior toattachment of the closure to the container, extending at least inwardlyinto said cavity to a free edge positioned inwardly of the skirtportion, and the inner surface having a first substantially cylindricalsurface portion lying radially inwardly of the skirt portion and atleast a second substantially cylindrical surface portion lying radiallyinwardly of the first surface portion.
 2. The closure of claim 1 whereinthe first surface portion is cylindrical.
 3. The closure of claim 2wherein the second surface portion is cylindrical.
 4. The closure ofclaim 1 wherein the transition between the inner diameter of the firstsurface portion and the smaller inner diameter of the second surfaceportion of the inner surface of the closure is substantiallyfrusto-conical.
 5. The closure of claim 1 wherein the closure comprisesan annular sealing rib, said rib including the first sealing portion andthe second sealing portion.
 6. The closure of claim 5 wherein the firstsealing portion of the sealing rib is contiguous with the top portionand projects downwardly from an underside of the top portion.
 7. Theclosure of claim 6 wherein the second portion is contiguous with an endof the first portion distal the closure top portion and extends for alength inwardly and downwardly from the distal end of the first portionto said circular free edge.
 8. The closure of claim 7 wherein the secondportion is substantially frusto-conical for at least a portion of itslength.
 9. The closure of claim 8 wherein the second sealing portion ismolded at an angle of between about 25° and 75° relative to a notionalplane extending at a right angle to the skirt portion of the closure.10. The closure of claim 9 wherein the length of the second portion issuch that, during attachment of the closure with the end portion of thecontainer, the end portion of the container contacts the second portionand pushes it upwardly and towards the first sealing portion of theclosure.
 11. The closure of claim 1 wherein the underside of the topportion of the closure has a nub extending downwardly from the undersideof the top portion and positioned radially inwardly of the inner surfaceof the first sealing portion of the closure, said nub being positionedsuch that, during relative attachment of the closure with the endportion of the container, the nub contacts the inner surface of the endportion of the container.
 12. The closure of claim 11 wherein the nubcomprises a continuous member having an inner surface, an outer surface,and which extends downwardly and outwardly from the top portion to anend distal the top portion.
 13. The closure of claim 12 wherein theouter surface of the nub has a contact surface that extends upwardlyfrom the distal end of the nub for a portion of the outer surface andwhich contacts the inner surface of the container end portion onrelative attachment of the closure to the container end portion.
 14. Theclosure of claim 12 wherein the nub extends downwardly from the topportion for a length substantially equal to the length of the innersurface of the first sealing portion.
 15. The closure of claim 1 whereinthe first sealing portion comprises a thickening of the skirt portionthat is also contiguous with an underside of the closure top portion.16. A closure suitable for attachment to a container having an endportion defining an opening of the container, the closure comprising: atop portion; a skirt portion depending from the top portion, said topportion and skirt portion defining a cavity; an annular sealing ribhaving, prior to attachment of the closure to the container, at least aportion extending inwardly into said cavity to a free edge; and acontinuous nub member extending downwardly and outwardly from theunderside of the top portion and positioned radially inwardly of thesealing rib, wherein on relative attachment of the closure to thecontainer end portion, the nub member seals with an inner surface of thecontainer end portion and the annular sealing rib seals with at least anouter surface of the container end portion.
 17. The closure of claim 16wherein an outer surface of the nub has a contact surface that extendsupwardly from an end of the nub distal the top portion for a portion ofthe outer surface and which contacts the inner surface of the containerend portion on relative attachment of the closure to the container endportion.
 18. A closure suitable for attachment to a container having anend portion defining an opening of the container, the closurecomprising: a top portion; a skirt portion depending from the topportion, said top portion and skirt portion defining a cavity; a sealingrib having: a first sealing portion which is at least adjacent the topportion and having an inner surface, said inner surface having a firstsubstantially cylindrical surface portion lying radially inwardly of theskirt portion and at least a second substantially cylindrical surfaceportion lying radially inwardly of the first surface portion; and asecond sealing portion, separated from the top portion by the innersurface of the first portion and having, prior to attachment of theclosure to the container, at least a portion extending inwardly intosaid cavity to a free edge; and a continuous nub member extendingdownwardly and outwardly from the underside of the top portion andpositioned radially inwardly of the first sealing portion; wherein onrelative attachment of the closure to the container end portion, the nubmember seals with an inner surface of the container end portion and thesealing rib seals with at least an outer surface of the container endportion.
 19. A container having an end portion defining an opening ofthe container, the end portion being sealed by a closure as defined inclaim
 1. 20. A mold for forming a closure as defined in claim 1 whereinthe mold has a cavity defining the features of the closure.
 21. A moldfor forming a closure as defined in claim 16 wherein the mold has acavity defining the features of the closure.
 22. A mold for forming aclosure as defined in claim 18 wherein the mold has a cavity definingthe features of the closure.
 23. A method of applying a closure asdefined in claim 1 to an end portion of a container, the methodcomprising a step of turning said closure onto the end portion of thecontainer until the closure seals the container.